Observational Analysis of Pedestrian, Bicyclist, and Motorist Behaviors at Roundabouts in the United States

Roundabouts continue to gain popularity in the United States as an intersection treatment for improving operational efficiency and motor vehicle safety. A number of studies conducted in the United States and other countries have shown the benefits of roundabouts for these purposes. However, there is still concern that roundabouts may not provide safety or operational benefits for pedestrians and bicyclists. Crash-based studies of pedestrian and bicyclist safety in the United States have fallen short because of the relatively small number of roundabouts installed to date, which results in sample size issues due to the low number of motor vehicle collisions involving pedestrians and bicyclists. This study was undertaken as part of an NCHRP project. This paper focused on analyzing the interactions between motorists and pedestrians or bicyclists at roundabouts. This research did not find any substantial safety problems for nonmotorists at roundabouts based on conflicts or collisions. At the same time, the findings from behavioral observation have highlighted some aspects of roundabout design that require additional care to ensure safe access for pedestrians and bicyclists. Emphasis needs to be placed on designing exit legs to ensure proper sight lines and motor vehicle speeds. The junction of the circulatory lane and exit lane was observed to be the location of greatest risk for bicyclists. Multilane roundabouts may require additional traffic control measures to ensure safe access for pedestrians.